Re: [RFC PATCH v5 v5 7/8] arm64: dts: rockchip: rk3576: add NPU (RKNN) nodes

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The device tree nodes are padded with fake power-domain dependencies to bypass the Linux driver core's single-domain auto-attach mechanism.
--

--- Patch [7]: [RFC PATCH v5 v5 7/8] arm64: dts: rockchip: rk3576: add NPU (RKNN) nodes ---
commit 2901ef2a9f2683429a8cc97e3be5786a1b6b21b5
Author: Jiaxing Hu <gahing@gahingwoo.com>

arm64: dts: rockchip: rk3576: add NPU (RKNN) nodes

Add the two RKNN cores and their IOMMUs for the rk3576. Both cores are
disabled by default, and boards can enable what they wire up. The NPU
power-domain resets are also added.

> diff --git a/arch/arm64/boot/dts/rockchip/rk3576.dtsi b/arch/arm64/boot/dts/rockchip/rk3576.dtsi
> --- a/arch/arm64/boot/dts/rockchip/rk3576.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3576.dtsi
[ ... ]
> @@ -1832,6 +1840,74 @@ qos_npu_m1ro: qos@27f22100 {
[ ... ]
> +		rknn_core_0: npu@27700000 {
> +			compatible = "rockchip,rk3576-rknn-core";
[ ... ]
> +			resets = <&cru SRST_A_RKNN0>;
> +			reset-names = "srst_a";
> +			power-domains = <&power RK3576_PD_NPU0>, <&power RK3576_PD_NPU1>;

[Severity: Medium]
Are these power domains accurately describing the hardware topology, or are they
encoding a software workaround? 

The commit message mentions that listing both domains prevents the driver core
from auto-attaching a single domain. Device trees should accurately describe the
hardware instead of encoding software workarounds to bypass driver core behavior.

[ ... ]
> +		rknn_core_1: npu@27708000 {
> +			compatible = "rockchip,rk3576-rknn-core";
[ ... ]
> +			resets = <&cru SRST_A_RKNN1>;
> +			reset-names = "srst_a";
> +			power-domains = <&power RK3576_PD_NPU1>, <&power RK3576_PD_NPU0>;

[Severity: Medium]
Will padding the power-domains list with RK3576_PD_NPU0 on rknn_core_1 cause
unintended side effects?

Since this artificially inflates the power-domain count to bypass the OS
auto-attach mechanism, it appears it will cause the system to unnecessarily
power on NPU0 when only Core 1 is active, wasting energy.

> +			iommus = <&rknn_mmu_1>;
> +			status = "disabled";
> +		};

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260805063826.95682-1-gahing@gahingwoo.com?part=7